Hi @Usman_Tahir,
Ah that would be because the transfers have to be manually processed by simulating bank transfer processing using one of two methods, 1) clicking the Process Bank Transfers button in the Sandbox Dashboard, or 2) calling the /sandbox-simulations endpoint via the API.
Check out this post about Masspayments for more information and recommendations on creating and handling masspayments - Mass Payments - Pay 5,000 People in Five Simple Steps
Hope that helps! 